When the
switch pin is driven with the value 0, the output accessor
will be
downstream1. When the
switch pin is driven with the value 1,
the output accessor will be
downstream2.
The
switch pin can be driven any number of times, each time
causing the corresponding output to be selected.
If the
switch pin is driven with a value other than 0 or 1, then
subsequent accesses to the input bus,
upstream, will return
sid::bus::unmapped.